Physical quantity sensor, physical quantity sensor device, electronic equipment, and moving body

ABSTRACT

A physical quantity sensor includes: an oscillating body having a support section and a movable section which is connected to the support section through connection portions, in which the movable section has a first movable portion and a second movable portion; a first fixed electrode which is disposed to face the first movable portion; a second fixed electrode which is disposed to face the second movable portion; and a dummy electrode which is disposed to face the second movable portion so as not to overlap the second fixed electrode and has the same potential as potential of the oscillating body, in which the first fixed electrode is disposed such that a portion thereof overlaps the support section when viewed in a plan view.

BACKGROUND

1. Technical Field

The present invention relates to a physical quantity sensor, a physicalquantity sensor device, electronic equipment, and a moving body.

2. Related Art

In recent years, a physical quantity sensor for detecting a physicalquantity such as acceleration by using, for example, a silicon microelectro mechanical systems (MEMS) technique has been developed.

As the physical quantity sensor, a physical quantity sensor having amovable electrode which has a large plate portion and a small plateportion and is supported on an insulating layer such that the plateportions can oscillate in a seesaw manner, a fixed electrode which isprovided on the insulating layer to face the large plate portion, and afixed electrode which is provided on the insulating layer to face thesmall plate portion is known (refer to, for example, JP-A-2007-298405).

In the physical quantity sensor described in JP-A-2007-298405, whenanodically bonding a structural body (a Si structural body) providedwith a movable electrode to a glass substrate, if a glass exposedsurface facing the structural body is large, an electrostatic forcewhich is generated increases, and therefore, there is a problem in thatsticking of the structural body to the glass substrate occurs.

In order to solve such a problem, an attempt to suppress sticking of amovable body to a substrate by providing an opposite electrode (a dummyelectrode) having the same potential as the potential of a movableelectrode has been made (refer to, for example, JP-A-2013-160554).

However, in the physical quantity sensor described in JP-A-2013-160554,the occurrence of sticking of the movable electrode can be reduced bythe dummy electrode. However, a difference in capacitance (a capacityoffset) between each fixed electrode and the movable electrode occurs,and according to the variation thereof, yield is deteriorated beyond anadjustment range of an integrated circuit (IC). Further, there is aproblem in that a capacity offset affects the entire sensor (refer to,for example, JP-A-2002-202320).

SUMMARY

The invention can be realized in the following aspects or applicationexamples.

Application Example 1

According to this application example, there is provided a physicalquantity sensor including: a movable electrode having a support sectionand a movable section which is connected to the support section througha connection portion and can oscillate with respect to the supportsection, in which the movable section has a first movable portion whichis provided on one side with respect to the connection portion, and asecond movable portion which is provided on the other side; a firstfixed electrode which is disposed to face the first movable portion; asecond fixed electrode which is disposed to face the second movableportion; and an opposite electrode which is disposed to face the secondmovable portion so as not to overlap the second fixed electrode and hasthe same potential as potential of the movable electrode, in which thefirst fixed electrode is disposed such that a portion thereof overlapsthe support section when viewed in a plan view.

In this way, a physical quantity sensor in which it is possible toreduce deviation of capacitance is obtained.

Application Example 2

In the physical quantity sensor according to the above-describedApplication Example, it is preferable that the second fixed electrode isdisposed such that a portion thereof overlaps the support section whenviewed in a plan view, and when an area of a region overlapping thesupport section, of the first fixed electrode, is set to be S1 and anarea of a region overlapping the support section, of the second fixedelectrode, is set to be S2, a relationship of S1>S2 is satisfied.

In this way, it is possible to more effectively reduce the deviation ofcapacitance.

Application Example 3

In the physical quantity sensor according to the above-describedApplication Example, it is preferable that, when capacitance which isgenerated between the first fixed electrode and the support section isset to be C1, capacitance which is generated between the second fixedelectrode and the support section is set to be C2, and capacitance whichis generated between the second fixed electrode and the oppositeelectrode is set to be C3, a relationship of (C2+C3)×0.9≦C1≦(C2+C3)×1.1is satisfied.

In this way, it is possible to sufficiently reduce the deviation ofcapacitance.

Application Example 4

In the physical quantity sensor according to the above-describedapplication example, it is preferable that the opposite electrode isdisposed on the side opposite to the support section, of the secondfixed electrode.

In this way, overlapping of the second fixed electrode with the supportsection is not inhibited.

Application Example 5

In the physical quantity sensor according to the above-describedapplication example, it is preferable that when the movable section isviewed in a plan view, the second movable portion has a larger area thanthe first movable portion.

In this way, it is possible to make the rotational moments of the firstmovable portion and the second movable portion different from each otherwith a simple configuration.

Application Example 6

In the physical quantity sensor according to the above-describedapplication example, it is preferable that the support section isdisposed in an opening and located between the first movable portion andthe second movable portion when viewed in a plan view.

In this way, it is possible to overlap the support section and the firstand second fixed electrode with a simple configuration.

Application Example 7

In the physical quantity sensor according to the above-describedapplication example, it is preferable that the movable section has anopening portion between the first movable portion and the second movableportion and the support section is disposed in the opening portion.

In this way, the configuration of the movable electrode is simplified.

Application Example 8

A physical quantity sensor device according to this application exampleincludes an electronic component which is electrically connected to thephysical quantity sensor.

In this way, a physical quantity sensor device having high reliabilityis obtained.

Application Example 9

Electronic equipment according to this application example includes thephysical quantity sensor according to any one of the above applicationexamples.

In this way, electronic equipment having high reliability is obtained.

Application Example 10

A moving body according to this application example includes thephysical quantity sensor according to any one of the above applicationexamples.

In this way, a moving body having high reliability is obtained.

Application Example 11

According to this application example, there is provided a physicalquantity sensor including: a substrate; a support section which is fixedto the substrate; a movable section which is connected to the supportsection through a connection portion and can oscillate with respect tothe support section; and a fixed electrode which is disposed on thesubstrate to face the movable section, in which the movable sectionincludes a first mass portion which is provided on one side with respectto the connection portion, a second mass portion which is provided onthe other side and has a mass larger than the first mass portion, afirst movable electrode disposed in the first mass portion, and a secondmovable electrode disposed in the second mass portion, the fixedelectrode includes a first fixed electrode which is disposed to face thefirst mass portion, a second fixed electrode which is disposed to facethe second mass portion, and a dummy electrode which is disposed to facethe movable section so as not to come into contact with the first fixedelectrode and the second fixed electrode and has the same potential aspotential of the movable section, the dummy electrode includes a firstdummy electrode provided between the first fixed electrode and thesecond fixed electrode, a second dummy electrode provided on the sideopposite to the first dummy electrode, of the first fixed electrode, anda third dummy electrode provided on the side opposite to the first dummyelectrode, of the second fixed electrode, and the fixed electrode andthe dummy electrode are disposed such that a capacity offset is smallerthan a capacity offset in a case where distances between the first fixedelectrode and the first and second dummy electrodes and distancesbetween the second fixed electrode and the first and third dummyelectrodes are the same.

In this way, it is possible to prevent the occurrence of sticking andreduce a capacity offset.

Application Example 12

In the physical quantity sensor according to the above-describedApplication Example, it is preferable that, when a distance between thefirst fixed electrode and the first dummy electrode is set to be w1, adistance between the second fixed electrode and the first dummyelectrode is set to be w2, a distance between the first fixed electrodeand the second dummy electrode is set to be w3, and a distance betweenthe second fixed electrode and the third dummy electrode is set to bew4, a relationship of w1<w2 and w3=w4 is satisfied.

In this way, it is possible to more easily reduce the capacity offset.

Application Example 13

In the physical quantity sensor according to the above-describedApplication Example, it is preferable that, when a distance between thefirst fixed electrode and the first dummy electrode is set to be w1, adistance between the second fixed electrode and the first dummyelectrode is set to be w2, a distance between the first fixed electrodeand the second dummy electrode is set to be w3, and a distance betweenthe second fixed electrode and the third dummy electrode is set to bew4, a relationship of w1<w2 and w3<w4 is satisfied.

In this way, it is possible to more easily reduce the capacity offset.

Application Example 14

In the physical quantity sensor according to the above-describedApplication Example, it is preferable that, when a distance between thefirst fixed electrode and the first dummy electrode is set to be w1, adistance between the second fixed electrode and the first dummyelectrode is set to be w2, a distance between the first fixed electrodeand the second dummy electrode is set to be w3, and a distance betweenthe second fixed electrode and the third dummy electrode is set to bew4, a relationship of w1<w2 and w3>w4 is satisfied.

In this way, it is possible to more easily reduce the capacity offset.

Application Example 15

In the physical quantity sensor according to the above-describedApplication Example, it is preferable that, when a distance between thefirst fixed electrode and the first dummy electrode is set to be w1, adistance between the second fixed electrode and the first dummyelectrode is set to be w2, a distance between the first fixed electrodeand the second dummy electrode is set to be w3, and a distance betweenthe second fixed electrode and the third dummy electrode is set to bew4, a relationship of w1>w2 and w3<w4 is satisfied.

In this way, it is possible to more easily reduce the capacity offset.

Application Example 16

In the physical quantity sensor according to the above-describedapplication example, it is preferable that the substrate is a glasssubstrate.

In this way, it is possible to easily electrically insulate the movablesection and the substrate, and thus it is possible to simplify a sensorstructure.

Application Example 17

According to this application example, there is provided a physicalquantity sensor including: a substrate; a support section which is fixedto the substrate; a movable section which is connected to the supportsection through a connection portion and can oscillate with respect tothe support section; and a fixed electrode which is disposed on thesubstrate to face the movable section, in which the movable sectionincludes a first mass portion which is provided on one side with respectto the connection portion, and a second mass portion which is providedon the other side and has a mass larger than the first mass portion, thefixed electrode includes a first fixed electrode which is disposed toface the first mass portion, a second fixed electrode which is disposedto face the second mass portion, and a dummy electrode which is disposedto face the movable section so as not to come into contact with thefirst fixed electrode and the second fixed electrode and has the samepotential as potential of the movable section, and when an axialdirection in which the movable section is oscillated is set to be aY-axis direction, at least one of a width in the Y-axis direction of thedummy electrode disposed alongside the first fixed electrode and a widthin the Y-axis direction of the first fixed electrode is larger than awidth in the Y-axis direction of the second fixed electrode.

In this way, it is possible to prevent the occurrence of the stickingand reduce the capacity offset.

Application Example 18

In the physical quantity sensor according to the above-describedapplication example, it is preferable that the dummy electrode has afirst portion which is disposed to face the first fixed electrode in theY-axis direction.

In this way, it is possible to more easily reduce the capacity offset.

Application Example 19

In the physical quantity sensor according to the above-describedapplication example, it is preferable that the first portion is providedin a pair so as to be located on both sides in the Y-axis direction ofthe first fixed electrode.

In this way, it is possible to more easily reduce the capacity offset.

Application Example 20

In the physical quantity sensor according to the above-describedapplication example, it is preferable that the first fixed electrode hasa second portion which is disposed to face the dummy electrode in theY-axis direction.

In this way, it is possible to more effectively prevent the occurrenceof the sticking while reducing the capacity offset.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a plan view (a top view) showing a physical quantity sensoraccording to a preferred embodiment of the invention.

FIG. 2 is a sectional view along line II-II of FIG. 1.

FIGS. 3A to 3C are schematic diagrams for describing the driving of thephysical quantity sensor shown in FIG. 1.

FIG. 4 is a partial enlarged sectional view of the physical quantitysensor shown in FIG. 1.

FIG. 5 is a sectional view showing an example of a physical quantitysensor device according to the invention.

FIG. 6 is a plan view showing a physical quantity sensor according to apreferred embodiment of the invention.

FIG. 7 is a sectional view along line VII-VII of FIG. 6, showing thephysical quantity sensor of FIG. 6.

FIG. 8 is a sectional view along line VIII-VIII of FIG. 6, showing thephysical quantity sensor of FIG. 6.

FIG. 9 is a sectional view along line IX-IX of FIG. 6, showing thephysical quantity sensor of FIG. 6.

FIG. 10 is a sectional view showing a process of manufacturing thephysical quantity sensor of FIG. 6.

FIG. 11 is a sectional view showing the process of manufacturing thephysical quantity sensor of FIG. 6.

FIG. 12 is a sectional view showing the process of manufacturing thephysical quantity sensor of FIG. 6.

FIG. 13 is a plan view showing a physical quantity sensor according to apreferred embodiment of the invention.

FIG. 14 is a plan view showing a physical quantity sensor according toModified Example 1.

FIG. 15 is a plan view showing a physical quantity sensor according toModified Example 2.

FIG. 16 is a plan view showing a physical quantity sensor according toModified Example 3.

FIG. 17 is a plan view showing a physical quantity sensor according toModified Example 4.

FIG. 18 is a plan view showing a physical quantity sensor according toModified Example 5.

FIG. 19 is a perspective view showing the configuration of a mobile type(or a notebook type) personal computer with electronic equipmentaccording to the invention applied thereto.

FIG. 20 is a perspective view showing the configuration of a mobilephone (also includes a PHS) with the electronic equipment according tothe invention applied thereto.

FIG. 21 is a perspective view showing the configuration of a digitalstill camera with the electronic equipment according to the inventionapplied thereto.

FIG. 22 is a perspective view showing an automobile with a moving bodyaccording to the invention applied thereto.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, a physical quantity sensor, electronic equipment, and amoving body according to the invention will be described in detail basedon embodiments shown in the accompanying drawings.

FIG. 1 is a plan view (a top view) showing a physical quantity sensoraccording to a preferred embodiment of the invention. FIG. 2 is asectional view along line II-II of FIG. 1. FIGS. 3A to 3C are schematicdiagrams for describing the driving of the physical quantity sensorshown in FIG. 1. FIG. 4 is a partial enlarged sectional view of thephysical quantity sensor shown in FIG. 1. In addition, in the following,for convenience of description, the front side of the plane of FIG. 1will be referred to as a “top” and the back side of the plane of FIG. 1will be referred to as a “bottom”. Further, in each of the drawings, asthree axes orthogonal to each other, an X-axis, a Y-axis, and a Z-axisare shown. Further, in the following, a direction parallel to the X-axiswill be referred to as an “X-axis direction”, a direction parallel tothe Y-axis will be referred to as a “Y-axis direction”, and a directionparallel to the Z-axis will be referred to as a “Z-axis direction”.

1. Physical Quantity Sensor

First, the physical quantity sensor according to the invention will bedescribed.

A physical quantity sensor 1 shown in FIGS. 1 and 2 can be used as, forexample, an inertial sensor and specifically, is available as anacceleration sensor for measuring acceleration in the Z-axis direction(a vertical direction). The physical quantity sensor 1 includes a basesubstrate 2, a lid body 3, and an oscillating body (a movable electrode)4 disposed in an internal space S formed by the base substrate 2 and thelid body 3.

Base Substrate

The base substrate 2 has a plate shape. Further, a concave portion 21which is open at a central portion excluding an edge portion of the basesubstrate 2 is formed in the upper surface of the base substrate 2. Theconcave portion 21 functions as an escape portion for preventing thecontact between the oscillating body 4 and the base substrate 2.Further, a convex portion 22 which protrudes in an island form from abottom surface 211 of the concave portion 21 is provided at a centralportion of the concave portion 21, and the oscillating body 4 is fixedto the convex portion 22 so as to be able to oscillate in a seesawmanner (rotate around an axis J). Further, the side surface of theconcave portion 21 and the side surface of the convex portion 22 areconfigured as inclined surfaces, whereby the routing of wiring from thebottom surface 211 of the concave portion 21 to the upper surface of thebase substrate 2 is facilitated, and thus poor formation, disconnection,or the like of the wiring is reduced. Further, concave portions 23, 24,and 25 which are disposed around the concave portion 21 and are open onthe upper surface are formed in the base substrate 2, and a portion of aconductor pattern 5 is disposed in each of the concave portions 23, 24,and 25.

As a constituent material of the base substrate 2, a material having aninsulation property is favorable, and in this embodiment, a glassmaterial is used. In this way, anodic bonding can be used for thejoining of the base substrate 2 and the oscillating body 4. However, asa constituent material of the base substrate 2, it is not limited to theglass material, and for example, a high resistance silicon material maybe used.

The conductor pattern 5 is formed on the base substrate 2. The conductorpattern 5 has, as electrodes, a first fixed electrode 51, a second fixedelectrode 52, and a dummy electrode 53 which are disposed on the bottomsurface 211 of the concave portion 21. Further, the conductor pattern 5has, as wiring, wiring 54 which is connected to the first fixedelectrode 51 in the concave portion 21 and routed in the concave portion23, wiring 55 which is connected to the second fixed electrode 52 in theconcave portion 21 and routed in the concave portion 24, and wiringwhich is connected to the dummy electrode 53 in the concave portion 21,connected to the oscillating body 4 at the convex portion 22, and routedin the concave portion 25. In addition, a groove 221 is formed in theupper surface of the convex portion 22, and the wiring 56 is routed inthe groove 221 and connected to the oscillating body 4 through anelectrically-conductive bump B at the top of the convex portion 22.Further, the conductor pattern 5 has, as terminals, a terminal 57 whichis disposed in the concave portion 23 and connected to the wiring 54, aterminal 58 which is disposed in the concave portion 24 and connected tothe wiring 55, and a terminal 59 which is disposed in the concaveportion 25 and connected to the wiring 56. The terminals 57, 58, and 59of the conductor pattern 5 having such a configuration are disposed soas to be exposed from the lid body 3, whereby the contact between theconductor pattern 5 and the outside (for example, an IC chip 102 whichwill be described later) becomes possible.

In addition, the detailed disposition or the effects of the first fixedelectrode 51, the second fixed electrode 52, and the dummy electrode 53will be described later.

As a constituent material of the conductor pattern 5, as long as it haselectrical conductivity, there is no particular limitation, and forexample, an oxide (a transparent electrode material) such as ITO (IndiumTin Oxide), IZO (Indium Zinc Oxide), In₃O₃, SnO₂, Sb-containing SnO₂, orAl-containing ZnO, Au, Pt, Ag, Cu, Al, or an alloy containing these, orthe like can be given, and among these, one type or two or more typescan be used in combination.

Oscillating Body

The oscillating body 4 is provided above the base substrate 2, as shownin FIGS. 1 and 2. The oscillating body 4 has a support section 41, amovable section 42, and a pair of connection portions 43 and 44 whichconnects the movable section 42 and the support section 41 so as toallow the movable section 42 to oscillate with respect to the supportsection 41. Then, a configuration is made such that the movable section42 oscillates with respect to the support section 41 in a seesaw mannerwith the connection portions 43 and 44 as the axis J.

Further, the movable section 42 has a longitudinal shape (asubstantially rectangular shape) extending in the X-axis direction, andthe −X-axis direction side (one side) thereof is made to be a firstmovable portion 421 and the +X-axis direction side (the other side) ismade to be a second movable portion 422. Further, a plurality of slits421 a and 422 a which are provided in parallel in the X-axis directionand extend in the Y-axis direction are respectively formed in the firstand second movable portions 421 and 422. In this way, resistance to theseesaw oscillation of the movable section 42 is reduced. Further, anopening 423 is formed between the first movable portion 421 and thesecond movable portion 422, and the support section 41 and theconnection portions 43 and 44 are disposed on the inside of the opening423.

Further, the first and second movable portions 421 and 422 are designedsuch that rotational moments when acceleration in the vertical direction(the Z-axis direction) is applied thereto are different from each otherand predetermined inclination occurs in the movable section according tothe acceleration. In this way, if acceleration in the vertical directionoccurs, the movable section 42 oscillates in a seesaw manner around theaxis J. Specifically, in this embodiment, a design is made such that therotational moment of the second movable portion 422 becomes larger thanthe rotational moment of the first movable portion 421 by making thearea (the distance from the axis J to an end on the +X-axis side) of thesecond movable portion 422 larger than the area (the distance from theaxis J to an end on the −X-axis side) of the first movable portion 421,when viewed in a plan view, in other words, by making the mass of thesecond movable portion 422 larger than the mass of the first movableportion 421. With such a design, it is possible to easily make therotational moments of the first and second movable portions 421 and 422different from each other. Further, it is possible to sufficientlywidely form the dummy electrode 53, as will be described later.

In addition, as the shapes of the first and second movable portions 421and 422, as long as they have rotational moments different from eachother, as described above, there is no particular limitation, and forexample, a configuration is also acceptable in which the shapes in aplan view are the same and thicknesses are different. Further, aconfiguration is also acceptable in which the shapes are the same and aweight portion is disposed in either. The weight portion may be disposedas a separate body made of a weight material such as tungsten ormolybdenum, for example, and may also be formed integrally with themovable section 42.

Further, the support section 41 is disposed in the opening 423 andjoined to the convex portion 22 of the base substrate 2. Further, theconnection portions 43 and 44 are also disposed in the opening 423, andthe support section 41 and the movable section 42 are connected by theconnection portions 43 and 44. Further, the connection portions 43 andare coaxially located on both sides of the support section 41. In thisway, if acceleration in the vertical direction is applied, the movablesection 42 oscillates in a seesaw manner around the axis J while theconnection portions 43 and 44 are torsionally deformed.

Further, the support section 41 has a substantially H-shaped planarshape, as shown in FIG. 1. Specifically, the support section 41 has abase portion 411 which is located at a central portion and joined to theconvex portion 22 and to which the connection portions 43 and 44 areconnected, extending portions 412 and 413 which extend (protrude) froman end portion on the −X-axis side of the base portion 411 to both sidesin the Y-axis direction, and extending portions 414 and 415 which extendfrom an end portion on the +X-axis side of the base portion 411 to bothsides in the Y-axis direction. Then, the extending portions 412 and 413are located between the connection portions 43 and 44 and the firstmovable portion 421, and the extending portions 414 and 415 are locatedbetween the connection portions 43 and 44 and the second movable portion422. By providing the extending portions 412 to 415, it is possible tosufficiently widely secure each of the overlapping area of the supportsection 41 and the first fixed electrode 51 and the overlapping area ofthe support section 41 and the second fixed electrode 52, as will bedescribed later, and thus it is possible to perform the adjustment ofcapacitance within a wide range. In addition, the shape of the supportsection 41 is not particularly limited, and for example, the extendingportions 412 to 415 may be omitted.

In this embodiment, the oscillating body 4 is formed of a siliconsubstrate doped with impurities such as phosphorus or boron. In thisway, it is possible to perform processing with high precision byetching, and therefore, it is possible to provide the oscillating body 4with excellent dimensional precision. Further, it is possible to jointhe oscillating body 4 to the base substrate 2 (the convex portion 22)by anodic bonding. However, as a material of the oscillating body 4, itis not limited to silicon. Further, a method of providing electricalconductivity is also not limited to doping, and for example, a conductorlayer such as metal may be formed on the surface of the movable section42.

The disposition of the first and second fixed electrodes 51 and 52 andthe dummy electrode 53 with respect to the oscillating body 4 is asfollows. That is, as shown in FIGS. 1 and 2, the first fixed electrode51 is disposed on the bottom surface 211 so as to face the first movableportion 421 and forms capacitance Ca between itself and the firstmovable portion 421. Further, the second fixed electrode 52 is disposedon the bottom surface 211 so as to face the second movable portion 422and forms capacitance Cb between itself and the second movable portion422. Further, the dummy electrode 53 is located so as to face the secondmovable portion 422 and is further toward the +X-axis direction side(the tip side of the second movable portion 422) than the second fixedelectrode 52. The first and second fixed electrodes 51 and 52 and thedummy electrode 53 are disposed so as not to overlap by being separatedfrom each other and are insulated from each other.

Among the three electrodes 51 to 53, the first and second fixedelectrodes 51 and 52 are electrodes which are used for accelerationsensing, and the remaining dummy electrode 53 is an electrode forreducing the occurrence of sticking at the time of manufacturing. Asdescribed above, the oscillating body 4 (more precisely, a siliconsubstrate before patterning of the oscillating body 4) and the basesubstrate 2 are joined to each other by anodic bonding. However, thereis a case where an electrostatic force is generated between theoscillating body 4 and the base substrate 2 due to voltage which isapplied at this time and the oscillating body 4 is stuck to the basesubstrate 2 by the electrostatic force. For this reason, in thisembodiment, the dummy electrode 53 having the same potential as thepotential of the oscillating body 4 is provided on the surface (thebottom surface 211) facing the oscillating body 4, of the base substrate2, thereby reducing the electrostatic force, and thus the sticking ofthe oscillating body 4 to the base substrate 2 as described above isreduced.

Lid Body

The lid body 3 has a concave portion 31 which is open at the lowersurface, and is joined to the base substrate 2 such that the concaveportion 31 forms the internal space S along with the concave portion 21.In this embodiment, the lid body 3 is formed of a silicon substrate. Inthis way, the lid body 3 and the base substrate 2 can be joined to eachother by anodic bonding. In addition, in a state where the lid body 3 issimply joined to the base substrate 2, the inside and the outside of theinternal space S communicate with each other through the concaveportions 23, 24, and 25 formed in the base substrate 2. For this reason,in this embodiment, as shown in FIG. 2, the concave portions 23, 24, and25 are sealed by a SiO₂ film 6 formed by a TEOSCVD method or the like,and thus the internal space S is hermetically sealed.

The configuration of the physical quantity sensor 1 has been brieflydescribed above. In the physical quantity sensor 1, it is possible todetect acceleration in the vertical direction in the following manner.In a case where acceleration in the vertical direction is not applied tothe physical quantity sensor 1, the movable section 42 maintains ahorizontal state, as shown in FIG. 3A. Then, if vertical downward(−Z-axis direction) acceleration G1 is applied to the physical quantitysensor 1, due to the different rotational moments of the first andsecond movable portions 421 and 422, the movable section 42 oscillatesin a seesaw manner in a clockwise direction with the axis J as thecenter, as shown in FIG. 3B. On the contrary, if vertical upward(+Z-axis direction) acceleration G2 is applied to the physical quantitysensor 1, the movable section 42 oscillates in a seesaw manner in acounterclockwise direction with the axis J as the center, as shown inFIG. 3C. Due to the seesaw oscillation of the movable section 42, thedistance between the first movable portion 421 and the first fixedelectrode 51 and the distance between the second movable portion 422 andthe second fixed electrode 52 change, and accordingly, the capacitanceCa and the capacitance Cb change. For this reason, it is possible todetect the value of acceleration based on the amount of change of thecapacitance Ca and Cb (differential signals of the capacitance Ca andCb). Further, it is possible to identify the direction of acceleration(whether it is acceleration on the −Z-axis side or acceleration on the+Z-axis side) from the direction of a change in the capacitance Ca andCb. In this way, it is possible to detect acceleration by using thephysical quantity sensor 1.

In this manner, in the physical quantity sensor 1, acceleration isdetected based on the differential signals of the capacitance Ca and Cb,and therefore, it is preferable that a design is made such that thecapacitance Ca and the capacitance Cb are approximately equal to eachother in a state where acceleration is not applied. With such a design,it is possible to more accurately detect the received acceleration. Forthis reason, in this embodiment, the movable section 42 is disposedsubstantially parallel to the bottom surface 211, and thus the gapbetween the first fixed electrode 51 and the first movable portion 421and the gap between the second fixed electrode 52 and the second movableportion 422 become substantially equal to each other, and the area of aregion overlapping the first movable portion 421, of the first fixedelectrode 51, and the area of a region overlapping the second movableportion 422, of the second fixed electrode 52, are made to besubstantially equal to each other. In this way, the capacitance Ca andthe capacitance Cb are made to be substantially equal to each other.Further, there is also a case where the capacitance Ca and thecapacitance Cb are slightly deviated from each other according tomanufacturing accuracy, and therefore, in such a case, a correction ofmaking the offset of the capacitance Ca and Cb become zero is performedby using a correction circuit or the like included in the IC chip 102(described later).

Here, in fact, the capacitance Ca is detected as capacitance Ca′ betweenthe terminals 57 and 59, and the capacitance Cb is detected ascapacitance Cb′ between the terminals 58 and 59. Therefore, even if adesign is made such that the capacitance Ca and the capacitance Cb areequal to each other, there is a case where a difference occurs betweenthe capacitance Ca′ and the capacitance Cb′ due to the influence ofparasitic capacitance or the like. If a difference ΔC′ between thecapacitance Ca′ and the capacitance Cb′ is small (is within apredetermined range), the correction by the IC chip 102 becomespossible, as described above, and thus there is no problem. However, ifthe difference ΔC′ is large (is outside a predetermined range), thecorrection by the IC chip 102 as described above is not possible. Insuch a case, it is not possible to ensure detection accuracy, and as aresult, the manufacturing yield of the physical quantity sensor 1 isreduced.

Therefore, in the physical quantity sensor 1, a configuration is made inwhich preferably, the difference ΔC′ between the capacitance Ca′ and thecapacitance Cb′ can become zero such that it is possible to make thedifference ΔC′ be within a correction range of the IC chip 102.Hereinafter, this will be described in detail. In the physical quantitysensor 1, as described above, the dummy electrode 53 is disposed next tothe second fixed electrode 52, and therefore, capacitance (parasiticcapacitance) C3 is formed between the second fixed electrode 52 and thedummy electrode 53, as shown in FIG. 2. For this reason, the capacitanceC3 is added to the capacitance Cb′, and thus the capacitance Cb′ becomeslarger than the capacitance Ca′.

Therefore, in the physical quantity sensor 1, as shown in FIG. 4, thefirst fixed electrode 51 is disposed such that a portion thereofoverlaps the support section 41 when viewed in a plan view, and thuscapacitance C1 is formed between the first fixed electrode 51 and thesupport section 41, and similarly, the second fixed electrode 52 isdisposed such that a portion thereof overlaps the support section 41when viewed in a plan view, and thus capacitance C2 is formed betweenthe second fixed electrode 52 and the support section 41. Then, thedifference ΔC′ is reduced by adjusting the magnitude of the capacitanceC1 and C2. Specifically, as shown in FIG. 4, a configuration is madesuch that when the area of a region 51 a facing the support section 41,of the first fixed electrode 51 when viewed in a plan view, is set to beS1 and the area of a region 52 a facing the support section 41, of thesecond fixed electrode 52, is set to be S2, a relationship of S1>S2 issatisfied. For this reason, the capacitance C1 becomes larger than thecapacitance C2, and accordingly, it is possible to make the differenceΔC′ small (preferably, zero). Therefore, it is possible to make thedifference ΔC′ be within the correction range of the IC chip 102, andthus the manufacturing yield of the physical quantity sensor 1 isimproved.

Here, as the relationship between the capacitance C1, C2, and C3, aslong as it is possible to exhibit the above effect, there is noparticular limitation. However, for example, it is preferable to satisfya relationship of (C2+C3)×0.9≦C1≦(C2+C3)×1.1, and it is more preferableto satisfy a relationship of (C2+C3)=C1. In this way, it is possible tomore remarkably exhibit the above-described effect.

In particular, in this embodiment, the support section 41 is disposedbetween the first movable portion 421 and the second movable portion422, and therefore, for example, by extending the first and second fixedelectrodes 51 and 52 to the support section 41 side, it is possible toeasily form the regions 51 a and 52 a described above. For this reason,the configuration of the physical quantity sensor 1 becomes simple.Further, as in this embodiment, by forming the opening 423 between thefirst movable portion 421 and the second movable portion 422 anddisposing the support section 41 in the opening 423, the configurationof the oscillating body 4 becomes simple.

Further, the dummy electrode 53 is located on the +X-axis side (the sideopposite to the support section 41) of the second fixed electrode 52,and therefore, the formation of the region 52 a of the second fixedelectrode 52 is not inhibited by the dummy electrode 53. Also in thisregard, the configuration of the physical quantity sensor 1 becomessimple.

In addition, in this embodiment, the capacitance C2 is formed. However,the capacitance C2 may not be formed. That is, the second fixedelectrode 52 may be disposed so as not to overlap the support section 41when viewed in a plan view. Also by this, it is possible to exhibit thesame effect as described above. Further, in this embodiment, as theparasitic capacitance, only the capacitance C3 is taken into account.However, in addition to this, the magnitude of the capacitance C1 and C2may be adjusted in consideration of capacitance which is formed betweenthe wiring 54 and the wiring 56, capacitance which is formed between thewiring 55 and the wiring 56, or the like.

2. Physical Quantity Sensor Device

Next, the physical quantity sensor device according to the inventionwill be described.

FIG. 5 is a sectional view showing an example of the physical quantitysensor device according to the invention.

A physical quantity sensor device 100 shown in FIG. 5 includes asubstrate 101, the physical quantity sensor 1 fixed to the upper surfaceof the substrate 101 through an adhesion layer 103, and the IC chip (anelectronic component) 102 fixed to the upper surface of the physicalquantity sensor 1 through an adhesion layer 104. Then, the physicalquantity sensor 1 and the IC chip 102 are molded by a molding material Min a state where the lower surface of the substrate 101 is exposed. Inaddition, as the adhesion layers 103 and 104, for example, solder,silver paste, a resin-based adhesive (a die attaching agent), or thelike can be used. Further, as the molding material M, for example,thermosetting epoxy resin can be used, and it is possible to performmolding by, for example, a transfer molding method.

Further, a plurality of terminals 101 a are disposed on the uppersurface of the substrate 101, and a plurality of mounting terminals 101b which are connected to the terminals 101 a through internal wiring(not shown) or a castellation are disposed on the lower surface of thesubstrate 101. As the substrate 101, there is no particular limitation.However, for example, a silicon substrate, a ceramic substrate, a resinsubstrate, a glass substrate, a glass epoxy substrate, or the like canbe used.

Further, in the IC chip 102, for example, a drive circuit for drivingthe physical quantity sensor 1, a correction circuit for correcting thedifference ΔC′ described above, a detection circuit for detectingacceleration from the differential signals of the capacitance Ca′ andCb′, an output circuit for converting a signal from the detectioncircuit into a predetermined signal and outputting the converted signal,and the like are included. The IC chip 102 is electrically connected tothe terminals 57, 58, and 59 of the physical quantity sensor 1 throughbonding wires 105 and electrically connected to the terminals 101 a ofthe substrate 101 through bonding wires 106.

The physical quantity sensor device 100 has excellent reliability,because it is provided with the physical quantity sensor 1.

Next, a physical quantity sensor of FIG. 6 will be described withreference to the drawings.

FIG. 6 is a plan view showing a physical quantity sensor 200 accordingto a preferred embodiment of the invention, FIG. 7 is a sectional viewalong line VII-VII of FIG. 6, showing the physical quantity sensor 200of FIG. 6, FIG. 8 is a sectional view along line VIII-VIII of FIG. 6,showing the physical quantity sensor 200 of FIG. 6, and FIG. 9 is asectional view along line IX-IX of FIG. 6, showing the physical quantitysensor 200 of FIG. 6.

In addition, for convenience, in FIG. 6, illustration is made to seethrough a lid body 580. Further, in FIGS. 8 and 9, illustration is madewith the lid body 580 omitted. Further, in FIGS. 6 to 9, as three axesorthogonal to each other, the X-axis, the Y-axis, and the Z-axis areshown.

The physical quantity sensor 200 includes a substrate 510, a movablesection 520, connection portions 530 and 532, a support section 540,fixed electrodes 550 and 552, dummy electrodes 553, 554, and 555, wiring560, 564, and 566, pads 570, 572, and 574, and the lid body 580, asshown in FIGS. 6 to 9.

In addition, in this embodiment, an example will be described in whichthe physical quantity sensor 200 is an acceleration sensor (acapacitance type MEMS acceleration sensor) which detects acceleration inthe vertical direction (the Z-axis direction).

Hereinafter, the respective sections configuring the physical quantitysensor 200 will be sequentially described in detail.

A material of the substrate 510 is, for example, an insulating materialsuch as glass. For example, the substrate 510 is made of an insulatingmaterial such as glass and the movable section 520 is made of asemiconductor material such as silicon, whereby the two can be easilyelectrically insulated from each other, and thus it is possible tosimplify a sensor structure. In addition, in a case where the substrate510 is configured with glass, it is possible to provide a more sensitivephysical quantity sensor.

A concave portion 511 is formed in the substrate 510. The movablesection 520 and the connection portions 530 and 532 are provided abovethe concave portion 511 with a gap interposed therebetween. In theexample shown in FIG. 6, the planar shape (the shape as viewed from theZ-axis direction) of the concave portion 511 is a rectangular shape. Apost portion 513 is provided on a bottom surface (the surface of thesubstrate 510 defining the concave portion 511) 512 of the concaveportion 511.

In the example shown in FIGS. 7 to 9, the post portion 513 is providedintegrally with the substrate 510. The post portion 513 protrudesfurther upward (in the +Z-axis direction) than the bottom surface 512.

As shown in FIGS. 8 and 9, in this embodiment, the height of the postportion 513 (the distance between an upper surface 514 of the postportion 513 and the bottom surface 512) and the depth of the concaveportion 511 are configured so as to be equal to each other.

The upper surface 514 of the post portion 513 is joined to the supportsection 540. A depression portion 515 is formed in the upper surface 514of the post portion 513. The first wiring 560 is provided on a bottomsurface (the surface of the post portion 513 defining the depressionportion 515) 516 of the depression portion 515.

In addition, in the example shown in FIGS. 7 to 9, the side surface ofthe concave portion 511 (the side surface of the substrate 510 definingthe concave portion 511) and the side surface of the post portion 513are perpendicular to the bottom surface 512 of the concave portion 511.However, the side surfaces may be inclined with respect to the bottomsurface 512.

The movable section 520 is deformable around a support axis (a firstaxis) Q. Specifically, the movable section 520 oscillates in a seesawmanner with the support axis Q which is determined by the connectionportions 530 and 532 as a rotation axis (an oscillation axis), ifacceleration in the vertical direction (the Z-axis direction) is appliedthereto. The support axis Q is parallel to, for example, the Y-axis. Inthe illustrated example, the planar shape of the movable section 520 isa rectangular shape. The thickness (the size in the Z-axis direction) ofthe movable section 520 is constant, for example.

The movable section 520 has a first mass portion 520 a and a second massportion 520 b.

The first mass portion 520 a is one (a portion which is located on theright side in FIG. 6) of two portions of the movable section 520, whichare partitioned by the support axis Q, when viewed in a plan view.

The second mass portion 520 b is the other (a portion which is locatedon the left side in FIG. 6) of the two portions of the movable section520, which are partitioned by the support axis Q, when viewed in a planview.

In a case where acceleration in the vertical direction (for example,gravitational acceleration) is applied to the movable section 520, arotational moment (a moment of a force) is generated in each of thefirst mass portion 520 a and the second mass portion 520 b. Here, in acase where the rotational moment (for example, the rotational moment inthe clockwise direction) of the first mass portion 520 a and therotational moment (for example, the rotational moment in thecounterclockwise direction) of the second mass portion 520 b arebalanced, a change does not occur in the inclination of the movablesection 520, and thus it is not possible to detect acceleration.Therefore, the movable section 520 is designed such that whenacceleration in the vertical direction is applied, the rotational momentof the first mass portion 520 a and the rotational moment of the secondmass portion 520 b are not balanced, and thus predetermined inclinationoccurs in the movable section 520.

In the physical quantity sensor 200, by disposing the support axis Q ata position deviated from the center (the centroid) of the movablesection 520 (by making the distances from the support axis Q to the tipsof the mass portions 520 a and 520 b different from each other), themass portions 520 a and 520 b have masses different from each other.That is, in the movable section 520, masses are different on one side(the first mass portion 520 a) and the other side (the second massportion 520 b) with the support axis Q as a boundary. In the illustratedexample, the distance from the support axis Q to an end face 523 of thefirst mass portion 520 a is shorter than the distance from the supportaxis Q to an end face 524 of the second mass portion 520 b. Further, thethickness of the first mass portion 520 a and the thickness of thesecond mass portion 520 b are the same. Therefore, the mass of the firstmass portion 520 a is smaller than the mass of the second mass portion520 b. In this manner, the mass portions 520 a and 520 b have massesdifferent from each other, whereby when acceleration in the verticaldirection is applied, it is possible to make the rotational moment ofthe first mass portion 520 a and the rotational moment of the secondmass portion 520 b not be balanced. Therefore, when acceleration in thevertical direction is applied, it is possible to make predeterminedinclination occur in the movable section 520.

The movable section 520 is provided to be spaced apart from thesubstrate 510. The movable section 520 is provided above the concaveportion 511. In the illustrated example, a gap is provided between themovable section 520 and the substrate 510. Further, the movable section520 is provided to be spaced apart from the support section 540 by theconnection portions 530 and 532. In this way, the movable section 520can oscillate in a seesaw manner.

The movable section 520 is provided with a first movable electrode 521and a second movable electrode 522 provided with the support axis Q as aboundary. The first movable electrode 521 is provided in the first massportion 520 a. The second movable electrode 522 is provided in thesecond mass portion 520 b.

The first movable electrode 521 is a portion overlapping the first fixedelectrode 550 when viewed in a plan view, of the movable section 520.The first movable electrode 521 forms capacitance C1 between itself andthe first fixed electrode 550. That is, the capacitance C1 is formed bythe first movable electrode 521 and the first fixed electrode 550.

The second movable electrode 522 is a portion overlapping the secondfixed electrode 552 when viewed in a plan view, of the movable section520. The second movable electrode 522 forms capacitance C2 betweenitself and the second fixed electrode 552. That is, the capacitance C2is formed by the second movable electrode 522 and the second fixedelectrode 552. In the physical quantity sensor 200, the movable section520 is configured with an electrically-conductive material (silicondoped with impurities), whereby the movable electrodes 521 and 522 areprovided. That is, the first mass portion 520 a functions as the firstmovable electrode 521, and the second mass portion 520 b functions asthe second movable electrode 522.

The capacitance C1 and the capacitance C2 are configured so as to becomeequal to each other, for example, in a state where the movable section520 shown in FIG. 7 is horizontal. The positions of the movableelectrodes 521 and 522 change according to the movement of the movablesection 520. The capacitance C1 and the capacitance C2 change accordingto the positions of the movable electrodes 521 and 522. A predeterminedpotential is provided to the movable section 520 through the connectionportions 530 and 532 and the support section 540.

A through-hole 525 passing through the movable section 520 is formed inthe movable section 520. In this way, it is possible to reduce theinfluence of air (resistance of air) when the movable section 520oscillates. The through-hole 525 is formed, for example, in a plurality.In the illustrated example, the planar shape of the through-hole 525 isa rectangular shape.

An opening portion 526 passing through the movable section 520 isprovided in the movable section 520. The opening portion 526 is providedon the support axis Q when viewed in a plan view. The connectionportions 530 and 532 and the support section 540 are provided in theopening portion 526. In the illustrated example, the planar shape of theopening portion 526 is a rectangular shape. The movable section 520 isconnected to the support section 540 through the connection portions 530and 532.

The connection portions 530 and 532 connect the movable section 520 andthe support section 540. The connection portions 530 and 532 function astorsion springs. In this way, the connection portions 530 and 532 canhave strong resilience against torsional deformation occurring in theconnection portions 530 and 532 due to the seesaw oscillation of themovable section 520.

The connection portions 530 and 532 are disposed on the support axis Qwhen viewed in a plan view. The connection portions 530 and 532 extendalong the support axis Q. The first connection portion 530 extends inthe +Y-axis direction from the support section 540. The secondconnection portion 532 extends in the −Y-axis direction from the supportsection 540.

The support section 540 is disposed in the opening portion 526. Thesupport section 540 is provided on the support axis Q when viewed in aplan view. A portion of the support section 540 is joined (connected) tothe upper surface 514 of the post portion 513. The support section 540supports the movable section 520 through the connection portions 530 and532. A connection area 546 to which the connection portions 530 and 532are connected and which is provided along the support axis Q, and acontact area 563 which is provided on the outside of the connection area546 when viewed in a plan view and is electrically connected to thefirst wiring 560 provided on the substrate are provided in the supportsection 540.

The support section 540 has a first portion 541 and second portions 542,543, 544, and 545. The support section 540 has a shape in which thefirst portion 541 extends along a second axis R intersecting(specifically, orthogonal to) the support axis Q and the second portions542, 543, 544, and 545 protrude from end portions of the first portion541. The second axis R is an axis parallel to the X-axis.

The first portion 541 of the support section 540 extends to intersect(specifically, to be orthogonal to) the support axis Q. The connectionportions 530 and 532 are joined to the first portion 541. The firstportion 541 is provided on the support axis Q when viewed in a plan viewand is spaced apart from the substrate 510. That is, a portion on thesupport axis Q, of the support section 540, is spaced apart from thesubstrate 510. In the example shown in FIG. 6, the planar shape of thefirst portion 541 is a rectangular shape. The first portion 541 extendsalong the second axis R.

The connection area 546 is provided in the first portion 541 of thesupport section 540. In the example shown in FIG. 6, the connection area546 is an area sandwiched between the connection portions 530 and 532,of the support section 540 when viewed in a plan view. In theillustrated example, the planar shape of the connection area 546 is arectangular shape. At least a portion of the connection area 546 is notfixed to the substrate 510.

The second portions 542, 543, 544, and 545 of the support section 540protrude (extend) from the end portions of the first portion 541. In theexample shown in FIG. 6, the planar shape of each of the second portions542, 543, 544, and 545 is a rectangular shape. The contact area 563 isprovided in each of the second portions 542, 543, 544, and 545.

The second portions 542 and 543 of the support section 540 extend in theopposite directions to each other along the support axis Q from the endportion on one side (specifically, the end portion in the −X-axisdirection) of the first portion 541. In the illustrated example, thesecond portion 542 extends in the +Y-axis direction from the end portionon one side of the first portion 541. The second portion 543 extends inthe −Y-axis direction from the end portion on one side of the firstportion 541. A portion of the second portion 542 and a portion of thesecond portion 543 are joined to the post portion 513.

The second portions 544 and 545 of the support section 540 extend in theopposite directions to each other along the support axis Q from the endportion on the other side (specifically, the end portion in the +X-axisdirection) of the first portion 541. In the illustrated example, thesecond portion 544 extends in the +Y-axis direction from the end portionon the other side of the first portion 541. The second portion 545extends in the −Y-axis direction from the end portion on the other sideof the first portion 541. A portion of the second portion 544 and aportion of the second portion 545 are joined to the post portion 513.

The support section 540 is provided with the portions 541, 542, 543,544, and 545 as described above, thereby having a H-shaped(substantially H-shaped) planar shape. That is, the first portion 541configures the crossbar of the H-shape. The second portions 542, 543,544, and 545 configure the vertical bars of the H-shape.

The movable section 520, the connection portions 530 and 532, and thesupport section 540 are provided in an integrated fashion. In theillustrated example, the movable section 520, the connection portions530 and 532, and the support section 540 configure a single structuralbody (silicon structural body) 502. The movable section 520, theconnection portions 530 and 532, and the support section 540 areprovided in an integrated fashion by patterning a single substrate(silicon substrate). Materials of the movable section 520, theconnection portions 530 and 532, and the support section 540 are siliconwith electrical conductivity given thereto by doping of impurities suchas phosphorus or boron, for example. In a case where the material of thesubstrate 510 is glass and the materials of the movable section 520, theconnection portions 530 and 532, and the support section 540 aresilicon, the substrate 510 and the support section 540 are joined toeach other by, for example, anodic bonding.

In the physical quantity sensor 200, the structural body 502 is fixed tothe substrate 510 by a single support section 540. That is, thestructural body 502 is fixed to the substrate 510 at one point (thesingle support section 540). Therefore, compared to, for example, a formin which a structural body is fixed to a substrate at two points (twosupport sections), it is possible to reduce the influence on theconnection portions 530 and 532 of stress occurring due to a differencebetween the coefficient of thermal expansion of the substrate 510 andthe coefficient of thermal expansion of the structural body 502, stresswhich is applied to a device at the time of packaging, or the like.

The fixed electrodes 550 and 552 are provided on the substrate 510. Inthe illustrated example, the fixed electrodes 550 and 552 are providedon the bottom surface 512 of the concave portion 511. The first fixedelectrode 550 is disposed to face the first movable electrode 521. Thefirst movable electrode 521 is located above the first fixed electrode550 with a gap interposed therebetween. The second fixed electrode 552is disposed to face the second movable electrode 522. The second movableelectrode 522 is located above the second fixed electrode 552 with a gapinterposed therebetween. The area of the first fixed electrode 550 andthe area of the second fixed electrode 552 are, for example, the same.The planar shape of the first fixed electrode 550 and the planar shapeof the second fixed electrode 552 are symmetrical with respect to thesupport axis Q, for example.

The dummy electrodes 553, 554, and 555 are provided on the substrate 510so as not to come into contact with the fixed electrodes 550 and 552.The dummy electrodes 553, 554, and 555 are configured so as to have thesame potential as the potential of the movable section 520. By disposingthe dummy electrodes 553, 554, and 555, it is possible to reduce thesize of a glass exposed surface facing the structural body 502, andtherefore, it is possible to reduce an electrostatic force which isgenerated during anodic bonding, and thus it is possible to effectivelysuppress the sticking of the structural body 502 to the substrate 510.

The first dummy electrode 553 is provided between the first fixedelectrode 550 and the second fixed electrode 552. Further, the seconddummy electrode 554 is provided on the side opposite to the first dummyelectrode 553, of the first fixed electrode 550. Further, the thirddummy electrode 555 is provided on the side opposite to the first dummyelectrode 553, of the second fixed electrode 552.

Incidentally, in general, in a case where the widths in the Y-axisdirection of a fixed electrode and a dummy electrode are the same, whenthe capacitance between the first fixed electrode 550 and the seconddummy electrode 554 is set to be C6 and the capacitance between thesecond fixed electrode 552 and the third dummy electrode 555 is set tobe C7, a relationship of C6<C7 is established, and therefore, if thedifference between capacity which is formed by the movable section 520and the first fixed electrode 550 and capacity which is formed by themovable section 520 and the second fixed electrode 552 is taken, acapacity offset corresponding to the difference between C6 and C7occurs.

In contrast, in this embodiment, a configuration is made such that thewidth (the width in the Y-axis direction) of the second dummy electrode554 is larger than the width (the width in the Y-axis direction) of thesecond fixed electrode 552. With such a configuration, it is possible toincrease C6. As a result, it is possible to effectively reduce thedifference between C6 and C7, and thus it is possible to reduce acapacity offset.

Materials of the fixed electrodes 550 and 552 and the dummy electrodes553, 554, and 555 are, for example, aluminum, gold, or ITO (Indium TinOxide). It is preferable that the materials of the fixed electrodes 550and 552 and the dummy electrodes 553, 554, and 555 are a transparentelectrode material such as ITO. This is because a transparent electrodematerial is used as the fixed electrodes 550 and 552 and the dummyelectrodes 553, 554, and 555, whereby in a case where the substrate 510is a transparent substrate (a glass substrate), it is possible to easilyvisually recognize foreign matter or the like existing on the fixedelectrodes 550 and 552 and the dummy electrodes 553, 554, and 555.

The first wiring 560 is provided on the substrate 510. The first wiring560 has a wiring layer portion 561 and a bump portion 562.

The wiring layer portion 561 of the first wiring 560 connects the firstpad 570 and the bump portion 562. In the illustrated example, the wiringlayer portion 561 extends from the first pad 570 to the bump portion 562through a first groove portion 517 formed in the substrate 510, theconcave portion 511, and the depression portion 515. A portion providedin the depression portion 515, of the wiring layer portion 561, overlapsthe support section 540 when viewed in a plan view. In the illustratedexample, the planar shape of the portion provided in the depressionportion 515, of the wiring layer portion 561, is an H-shape (asubstantially H-shape). A material of the wiring layer portion 561 isthe same as the material of the fixed electrodes 550 and 552, forexample.

The bump portion 562 of the first wiring 560 is provided on the wiringlayer portion 561. The bump portion 562 connects the wiring layerportion 561 and the support section 540 at the contact area 563. Thatis, the contact area 563 is an area where the first wiring 560 and thesupport section 540 are connected (are in contact with each other). Morespecifically, the contact area 563 is an area (a contact surface) whichis in contact with the support section 540, of the bump portion 562. Amaterial of the bump portion 562 is, for example, aluminum, gold, orplatinum.

The contact area 563 is disposed to avoid the support axis Q. That is,the contact area 563 is disposed to be spaced apart from the supportaxis Q. At least one contact area 563 is provided for each of one side(specifically, the +X-axis direction side) and the other side(specifically, the −X-axis direction side) with the support axis Q as aboundary, when viewed in a plan view. The contact areas 563 are providedon both sides of the connection area 546 with the support axis Q as aboundary, when viewed in a plan view. In the illustrated example, fourcontact areas 563 are provided so as to overlap the second portions 542,543, 544, and 545 of the support section 540 when viewed in a plan view.That is, the contact area 563 is provided to overlap each of endportions of the vertical bars of the support section 540 having anH-shape (a substantially H-shape) when viewed in a plan view. In theillustrated example, the planar shape of each of the contact areas 563is a rectangular shape.

The contact area 563 is located further toward the upper side than theupper surface (the joint surface between the post portion 513 and thesupport section 540) 514 of the post portion 513, as shown in FIGS. 8and 9. Specifically, when joining a silicon substrate to the substrate510 (details will be described later), the silicon substrate isdepressed by being pushed by the bump portion 562 of the first wiring560, and thus the contact area 563 is located further toward the upperside than the upper surface 514 of the post portion 513. For example,the support section 540 (the silicon substrate) is pushed by the bumpportion 562, whereby stress occurs in the support section 540.

In addition, although not shown in the drawings, if the first wiring 560and the support section 540 are in contact with each other, the supportsection 540 is not depressed and the contact area 563 and the uppersurface 514 of the post portion 513 may be at the same position in theZ-axis direction. That is, the contact area 563 and the upper surface514 may have the same height. Also in such a form, the first wiring 560and the support section 540 come into contact with each other, wherebystress occurs in the support section 540.

Further, although not shown in the drawings, each of the dummyelectrodes 553, 554, and 555 is connected to the first wiring 560,thereby having the same potential as the potential of the movablesection 520.

The second wiring 564 is provided on the substrate 510. The secondwiring 564 connects the second pad 572 and the first fixed electrode550. In the illustrated example, the second wiring 564 extends from thesecond pad 572 to the first fixed electrode 550 through a second grooveportion 518 and the concave portion 511. A material of the second wiring564 is the same as the materials of the fixed electrodes 550 and 552,for example.

The third wiring 566 is provided on the substrate 510. The third wiring566 connects the third pad 574 and the second fixed electrode 552. Inthe illustrated example, the third wiring 566 extends from the third pad574 to the second fixed electrode 552 through a third groove portion 519and the concave portion 511. A material of the third wiring 566 is thesame as the materials of the fixed electrodes 550 and 552, for example.

The pads 570, 572, and 574 are provided on the substrate 510. In theillustrated example, the pads 570, 572, and 574 are respectivelyprovided in the groove portions 517, 518, and 519 and connected to thewirings 560, 564, and 566. The pads 570, 572, and 574 are provided atpositions which do not overlap the lid body 580 when viewed in a planview. In this way, even in a state where the movable section 520 isaccommodated in the substrate 510 and the lid body 580, it is possibleto detect the capacitance C1 and C2 by the pads 570, 572, and 574.Materials of the pads 570, 572, and 574 are the same as the materials ofthe fixed electrodes 550 and 552, for example.

The lid body 580 is provided on the substrate 510. The lid body 580 isjoined to the substrate 510. The lid body 580 and the substrate 510 forma cavity 582 which accommodates the movable section 520. The cavity 582has, for example, an inert gas (for example, nitrogen gas) atmosphere. Amaterial of the lid body 580 is, for example, silicon. In a case wherethe material of the lid body 580 is silicon and the material of thesubstrate 510 is glass, the substrate 510 and the lid body 580 arejoined to each other by, for example, anodic bonding.

Next, an operation of the physical quantity sensor 200 will bedescribed.

In the physical quantity sensor 200, the movable section 520 oscillatesaround the support axis Q according to a physical quantity such asacceleration or angular velocity. The distance between the first movableelectrode 521 and the first fixed electrode 550 and the distance betweenthe second movable electrode 522 and the second fixed electrode 552change according to the movement of the movable section 520.Specifically, if, for example, vertical upward (+Z-axis direction)acceleration is applied to the physical quantity sensor 200, the movablesection 520 rotates in the counterclockwise direction, and thus thedistance between the first movable electrode 521 and the first fixedelectrode 550 becomes smaller and the distance between the secondmovable electrode 522 and the second fixed electrode 552 becomes larger.As a result, the capacitance C1 becomes larger and the capacitance C2becomes smaller. Further, if, for example, vertical downward (−Z-axisdirection) acceleration is applied to the physical quantity sensor 200,the movable section 520 rotates in the clockwise direction, and thus thedistance between the first movable electrode 521 and the first fixedelectrode 550 becomes larger and the distance between the second movableelectrode 522 and the second fixed electrode 552 becomes smaller. As aresult, the capacitance C1 becomes smaller and the capacitance C2becomes larger.

In the physical quantity sensor 200, the capacitance C1 is detected byusing the pads 570 and 572, and the capacitance C2 is detected by usingthe pads 570 and 574. Then, a physical quantity such as the direction orthe magnitude of acceleration, angular velocity, or the like can bedetected based on the difference between the capacitance C1 and thecapacitance C2 (by a so-called differential detection method).

As described above, the physical quantity sensor 200 can be used as aninertial sensor such as an acceleration sensor or a gyro sensor andspecifically, can be used as a capacitance type acceleration sensor formeasuring, for example, acceleration in the vertical direction (theZ-axis direction).

In the physical quantity sensor 200 described above, the fixedelectrodes 550 and 552 and the dummy electrodes 553, 554, and 555 aredisposed such that a capacity offset becomes smaller than a capacityoffset in a case where the distances between the first fixed electrode550 and the first and second dummy electrodes 553 and 554 and thedistances between the second fixed electrode 552 and the first and thirddummy electrodes 553 and 555 are the same.

With such a configuration, it is possible to prevent the occurrence ofthe sticking and reduce the capacity offset.

More specifically, for example, when the distance between the firstfixed electrode 550 and the first dummy electrode 553 is set to be w1,the distance between the second fixed electrode 552 and the first dummyelectrode 553 is set to be w2, the distance between the first fixedelectrode 550 and the second dummy electrode 554 is set to be w3, andthe distance between the second fixed electrode 552 and the third dummyelectrode 555 is set to be w4, a configuration is made such that arelationship of w1<w2 and w3=w4 is established.

With such a configuration, when the capacitance between the first fixedelectrode 550 and the first dummy electrode 553 is set to be C4, thecapacitance between the second fixed electrode 552 and the first dummyelectrode 553 is set to be C5, the capacitance between the first fixedelectrode 550 and the second dummy electrode 554 is set to be C6, andthe capacitance between the second fixed electrode 552 and the thirddummy electrode 555 is set to be C7, a relationship of C4=C5 and C6>C7is established, and thus it is possible to further reduce the capacityoffset.

Further, for example, a configuration is made such that a relationshipof w1<w2 and w3=w4 is established, whereby even if a relationship ofC6<C7 is established, by making a relationship of C4>C5 be established,it is possible to further reduce the capacity offset.

Further, for example, by making a configuration such that a relationshipof w1<w2 and w3<w4 is established, a relationship of C4>C5 and C6>C7 isestablished, and thus it is possible to further reduce the capacityoffset.

Further, for example, in a case of narrowing w1, by making aconfiguration such that a relationship of w1<w2 and w3>w4 isestablished, a relationship of C4>>C5 and C6<C7 is established, and thusit is possible to further reduce the capacity offset.

Further, for example, in a case of narrowing w3, by making aconfiguration such that a relationship of w1>w2 and w3<w4 isestablished, a relationship of C4<C5 and C6>>C7 is established, and thusit is possible to further reduce the capacity offset.

Further, in the physical quantity sensor 200 having the configuration asdescribed above, the dummy electrodes 553, 554, and 555 are not formedin a sensor area (an area where capacitance changes), and therefore,there is no concern that accuracy may be reduced due to the occurrenceof variation in measurement, or the like.

Method of Manufacturing Physical Quantity Sensor

Next, a method of manufacturing the physical quantity sensor of FIG. 6will be described with reference to the drawings. FIGS. 10 to 12 aresectional views showing a process of manufacturing the physical quantitysensor 200 of FIG. 6 and correspond to FIG. 7.

As shown in FIG. 10, the concave portion 511, the post portion 513 withthe depression portion 515 formed therein, and the groove portions 517,518, and 519 (refer to FIG. 6) are formed by patterning, for example, aglass substrate. The patterning is performed by, for example,photolithography and etching. By this process, it is possible to obtainthe substrate 510 with the concave portion 511, the post portion 513,and the groove portions 517, 518, and 519 formed therein.

Next, the fixed electrodes 550 and 552 and the dummy electrodes 553,554, and 555 are formed on the bottom surface 512 of the concave portion511. Next, the wiring layer portion 561 and the wirings 564 and 566 areformed on the substrate 510 (refer to FIG. 6). The wirings 564 and 566are respectively formed so as to be connected to the fixed electrodes550 and 552. Next, the bump portion 562 is formed on the wiring layerportion 561 (refer to FIGS. 8 and 9). In this way, it is possible toform the first wiring 560. The bump portion 562 is formed such that theupper surface thereof is located further toward the upper side than theupper surface 514 of the post portion 513. Next, the pads 570, 572, and574 are respectively formed so as to be connected to the wirings 560,564, and 566 (refer to FIG. 6).

The fixed electrodes 550 and 552, the wirings 560, 564, and 566, and thepads 570, 572, and 574 are formed by film formation by, for example, asputtering method or a CVD (Chemical Vapor Deposition) method, andpatterning. The patterning is performed by, for example,photolithography and etching.

As shown in FIG. 11, for example, a silicon substrate 602 is joined tothe substrate 510. The joining of the substrate 510 and the siliconsubstrate 602 is performed by, for example, anodic bonding. In this way,the substrate 510 and the silicon substrate 602 can be solidly joined toeach other. In addition, at the time of the anodic bonding, the siliconsubstrate 602 and the dummy electrodes 553, 554, and 555 have the samepotential, and therefore, the sticking of the silicon substrate 602 tothe substrate 510 is effectively suppressed. Further, when joining thesilicon substrate 602 to the substrate 510, the silicon substrate 602 isdepressed by being pushed by the bump portion 562 of the first wiring560, for example (refer to FIGS. 8 and 9). In this way, stress occurs inthe silicon substrate 602.

As shown in FIG. 12, after the silicon substrate 602 is thinned bygrinding by, for example, a grinder, the silicon substrate 602 ispatterned into a predetermined shape, and thus the movable section 520,the connection portions 530 and 532, and the support section 540 areformed in an integrated fashion. The patterning is performed byphotolithography and etching (dry etching), and as a more specificetching technique, it is possible to use a Bosch method.

As shown in FIG. 7, the lid body 580 is joined to the substrate 510, andthus the movable section 520 and the like are accommodated in the cavity582 which is formed by the substrate 510 and the lid body 580. Thejoining of the substrate 510 and the lid body 580 is performed by, forexample, anodic bonding. In this way, the substrate 510 and the lid body580 can be solidly joined to each other. This process is performed in aninert gas atmosphere, whereby the cavity 582 can be filled with inertgas.

Through the above processes, it is possible to manufacture the physicalquantity sensor 200.

Further, FIG. 13 is a plan view showing a physical quantity sensoraccording to a preferred embodiment of the invention. As shown in FIG.13, in a physical quantity sensor 300, the second dummy electrode 554may have a shape in which the second dummy electrode 554 wraps aroundthe sides of both end portions in a width direction of the first fixedelectrode 550. Specifically, the second dummy electrode 554 is formed ina C-shape having a base portion 591 b which is located on the +X-axisside of the first fixed electrode 550 and extends in the Y-axisdirection, a protrusion portion 592 b which is located on the +Y-axisside of the first fixed electrode 550 and protrudes from an end portionon the +Y-axis side of the base portion 591 b to the −X-axis side, and aprotrusion portion 593 b which is located on the −Y-axis side of thefirst fixed electrode 550 and protrudes in the −X-axis direction from anend portion on the −Y-axis side of the base portion 591 b. Theprotrusion portions 592 b and 593 b are respectively provided alongside(to face) the first fixed electrode 550 in the Y-axis direction and aredisposed to face each other with the first fixed electrode 550interposed therebetween.

With such a shape, a portion facing the first fixed electrode 550, ofthe second dummy electrode 554, increases, and therefore, it is possibleto more effectively increase the capacitance C6 between the first fixedelectrode 550 and the second dummy electrode 554, and thus it ispossible to make the difference between C6 and C7 smaller. As a result,it is possible to further reduce the capacity offset.

Modified Example 1 of Physical Quantity Sensor

Next, a physical quantity sensor according to a modified example of thephysical quantity sensor 200 will be described with reference to thedrawing. FIG. 14 is a plan view showing a physical quantity sensor 400according to the modified example. In addition, for convenience, in FIG.14, illustration is made to see through the lid body 580. Further, inFIG. 14, as three axes orthogonal to each other, the X-axis, the Y-axis,and the Z-axis are shown.

Hereinafter, in the physical quantity sensor 400 according to themodified example, members having the same function as the constituentmembers of the physical quantity sensor 200 of FIG. 6 are denoted by thesame reference numerals and a detailed description thereof is omitted.

In the physical quantity sensor 200, as shown in FIG. 6, the planarshape of the support section 540 is an H-shape (a substantiallyH-shape). In contrast, in the physical quantity sensor 400, as shown inFIG. 14, the planar shape of the support section 540 is a quadrangularshape (in the illustrated example, a rectangular shape).

In the physical quantity sensor 400, one contact area 563 is providedfor each of one side (specifically, the +X-axis direction side) and theother side (specifically, the −X-axis direction side) with the supportaxis Q as a boundary, when viewed in a plan view.

The physical quantity sensor 400 can have high reliability, similarly tothe physical quantity sensor 200.

Modified Example 2 of Physical Quantity Sensor

Next, a physical quantity sensor according to Modified Example 2 of theabove-described physical quantity sensor will be described withreference to the drawing. FIG. 15 is a plan view showing a physicalquantity sensor 600 according to Modified Example 2. In addition, forconvenience, in FIG. 15, illustration is made to see through the lidbody 580. Further, in FIG. 15, as three axes orthogonal to each other,the X-axis, the Y-axis, and the Z-axis are shown.

Hereinafter, in the physical quantity sensor 600 according to themodified example, members having the same function as the constituentmembers of the physical quantity sensor 300 of FIG. 13 are denoted bythe same reference numerals and a detailed description thereof isomitted.

In the physical quantity sensor 300, as shown in FIG. 13, the seconddummy electrode 554 has a shape in which the second dummy electrode 554wraps around the sides of both end portions in the width direction ofthe first fixed electrode 550. In contrast, in the physical quantitysensor 600, as shown in FIG. 15, the second dummy electrode 554 has ashape in which the second dummy electrode 554 wraps around only the sideof the end portion on one side in the width direction of the first fixedelectrode 550. Specifically, the second dummy electrode 554 is formed inan L-shape having the base portion 591 b which is located on the +X-axisside of the first fixed electrode 550 and extends in the Y-axisdirection, and the protrusion portion 592 b which is located on the+Y-axis side of the first fixed electrode 550 and protrudes in the−X-axis direction from the end portion on the +Y-axis side of the baseportion 591 b.

In the physical quantity sensor 600, similarly to the physical quantitysensor 300, it is possible to reduce the capacity offset, and thus thephysical quantity sensor 600 can have high reliability.

Modified Example 3 of Physical Quantity Sensor

Next, a physical quantity sensor according to Modified Example 3 of theabove-described physical quantity sensor will be described withreference to the drawing. FIG. 16 is a plan view showing a physicalquantity sensor 700 according to Modified Example 3. In addition, forconvenience, in FIG. 16, illustration is made to see through the lidbody 580. Further, in FIG. 16, as three axes orthogonal to each other,the X-axis, the Y-axis, and the Z-axis are shown.

Hereinafter, in the physical quantity sensor 700 according to themodified example, members having the same function as the constituentmembers of the physical quantity sensor 300 of FIG. 13 are denoted bythe same reference numerals and a detailed description thereof isomitted.

In the physical quantity sensor 300, as shown in FIG. 13, the seconddummy electrode 554 has a shape in which the second dummy electrode 554wraps around the sides of both end portions in the width direction ofthe first fixed electrode 550. In contrast, in the physical quantitysensor 700, as shown in FIG. 16, the first dummy electrode 553 has ashape in which the first dummy electrode 553 wraps around the sides ofboth end portions in the width direction of the first fixed electrode550. Specifically, the first dummy electrode 553 is formed in a C-shapehaving a base portion 591 a which is located on the −X-axis side of thefirst fixed electrode 550 and extends in the Y-axis direction, aprotrusion portion 592 a which is located on the +Y-axis side of thefirst fixed electrode 550 and protrudes from an end portion on the+Y-axis side of the base portion 591 a to the +X-axis side, and aprotrusion portion 593 a which is located on the −Y-axis side of thefirst fixed electrode 550 and protrudes in the +X-axis direction from anend portion on the −Y-axis side of the base portion 591 a. Theprotrusion portions 592 a and 593 a are respectively provided alongside(to face) the first fixed electrode 550 in the Y-axis direction and aredisposed to face each other with the first fixed electrode 550interposed therebetween.

With such a configuration, even in a relationship of (the capacitance C6between the first fixed electrode 550 and the second dummy electrode554)<(the capacitance C7 between the second fixed electrode 552 and thethird dummy electrode 555), it is possible to make the capacitance C4between the first fixed electrode 550 and the first dummy electrode 553larger than the capacitance C5 between the second fixed electrode 552and the first dummy electrode 553. As a result, it is possible to reducethe difference between capacity which is formed by the movable section520 and the first fixed electrode 550 and capacity which is formed bythe movable section 520 and the second fixed electrode 552, and thus itis possible to reduce the capacity offset.

Modified Example 4 of Physical Quantity Sensor

Next, a physical quantity sensor according to Modified Example 4 of theabove-described physical quantity sensor will be described withreference to the drawing. FIG. 17 is a plan view showing a physicalquantity sensor 800 according to Modified Example 4. In addition, forconvenience, in FIG. 17, illustration is made to see through the lidbody 580. Further, in FIG. 17, as three axes orthogonal to each other,the X-axis, the Y-axis, and the Z-axis are shown.

Hereinafter, in the physical quantity sensor 800 according to themodified example, members having the same function as the constituentmembers of the physical quantity sensor 700 of FIG. 16 are denoted bythe same reference numerals and a detailed description thereof isomitted.

In the physical quantity sensor 700, as shown in FIG. 16, the firstdummy electrode 553 has a shape in which the first dummy electrode 553wraps around the sides of both end portions in the width direction ofthe first fixed electrode 550. In contrast, in the physical quantitysensor 800, the first dummy electrode 553 has a shape in which the firstdummy electrode 553 wraps around only the side of the end portion on oneside in the width direction of the first fixed electrode 550.Specifically, the first dummy electrode 553 is formed in an L-shapehaving the base portion 591 a which is located on the −X-axis side ofthe first fixed electrode 550 and extends in the Y-axis direction, andthe protrusion portion 592 a which is located on the +Y-axis side of thefirst fixed electrode 550 and protrudes from the end portion on the+Y-axis side of the base portion 591 b to the +X-axis side.

In the physical quantity sensor 800, similarly to the physical quantitysensors 300 and 700, it is possible to reduce the capacity offset, andthus the physical quantity sensor 800 can have high reliability.

Modified Example 5 of Physical Quantity Sensor

Next, a physical quantity sensor according to Modified Example 5 of theabove-described physical quantity sensor will be described withreference to the drawing. FIG. 18 is a plan view showing a physicalquantity sensor 900 according to Modified Example 5. In addition, forconvenience, in FIG. 18, illustration is made to see through the lidbody 580. Further, in FIG. 18, as three axes orthogonal to each other,the X-axis, the Y-axis, and the Z-axis are shown.

Hereinafter, in the physical quantity sensor 900 according to themodified example, members having the same function as the constituentmembers of the physical quantity sensor 300 of FIG. 13 are denoted bythe same reference numerals and a detailed description thereof isomitted.

In the physical quantity sensor 300, as shown in FIG. 13, the seconddummy electrode 554 has a shape in which the second dummy electrode 554wraps around the sides of both end portions in the width direction ofthe first fixed electrode 550. In contrast, in the physical quantitysensor 900, as shown in FIG. 18, the first fixed electrode 550 has ashape in which the first fixed electrode 550 wraps around the sides ofboth end portions in the width direction of the second dummy electrode554. Specifically, the first fixed electrode 550 is formed in a C-shapehaving a base portion 591 which is located on the −X-axis side of thesecond dummy electrode 554, a protrusion portion 592 which is located onthe +Y-axis side of the second dummy electrode 554 and protrudes from anend portion on the +Y-axis side of the base portion 591 to the +X-axisside, and a protrusion portion 593 which is located on the −Y-axis sideof the second dummy electrode 554 and protrudes in the +X-axis directionfrom an end portion on the −Y-axis side of the base portion 591. Theprotrusion portions 592 and 593 are respectively provided alongside (toface) the second dummy electrode 554 in the Y-axis direction and aredisposed to face each other with the second dummy electrode 554interposed therebetween.

In the physical quantity sensor 900, similarly to the physical quantitysensor 300, it is possible to reduce the capacity offset, and thus thephysical quantity sensor 900 can have high reliability.

3. Electronic Equipment

Next, electronic equipment according to the invention will be described.

FIG. 19 is a perspective view showing the configuration of a mobile type(or a notebook type) personal computer with the electronic equipmentaccording to the invention applied thereto.

In this drawing, a personal computer 1100 is configured to include amain body section 1104 provided with a keyboard 1102, and a display unit1106 provided with a display section 1108, and the display unit 1106 issupported so as to be able to rotate with respect to the main bodysection 1104 through a hinge structure section. Any of the physicalquantity sensors 1, 200, 300, 400, 600, 700, 800, and 900 which measurea physical quantity such as acceleration or angular velocity formeasuring dropping or inclination of the personal computer 1100 ismounted on the personal computer 1100. Hereinafter, the physicalquantity sensor 1 will be described as a representative. In this manner,the physical quantity sensor 1 described above is mounted, whereby it ispossible to obtain the personal computer 1100 having high reliability.

FIG. 20 is a perspective view showing the configuration of a mobilephone (also includes a PHS) with the electronic equipment according tothe invention applied thereto.

In this drawing, a mobile phone 1200 is provided with an antenna (notshown), a plurality of operation buttons 1202, an ear piece 1204, and amouthpiece 1206, and a display section 1208 is disposed between theoperation buttons 1202 and the ear piece 1204. The physical quantitysensor 1 which measures a physical quantity such as acceleration orangular velocity for measuring dropping or inclination of the mobilephone 1200 is mounted on the mobile phone 1200. In this manner, thephysical quantity sensor 1 described above is mounted, whereby it ispossible to obtain the mobile phone 1200 having high reliability.

FIG. 21 is a perspective view showing the configuration of a digitalstill camera with the electronic equipment according to the inventionapplied thereto. In addition, in this drawing, connection with externalequipment is also shown in a simplified manner.

Here, an ordinary camera exposes a silver halide photographic film tolight through an optical image of a photographic subject, whereas adigital still camera 1300 produces an imaging signal (an image signal)by performing photoelectric conversion of an optical image of aphotographic subject through an imaging element such as a charge coupleddevice (CCD).

A configuration is made in which a display section 1310 is provided onthe back surface of a case (a body) 1302 in the digital still camera1300 and display is performed based on the imaging signal by the CCD,and the display section 1310 functions as a finder which displays aphotographic subject as an electronic image. Further, a light receivingunit 1304 which includes an optical lens (an imaging optical system),the CCD, or the like is provided on the front side (the back side in thedrawing) of the case 1302.

If a photographer confirms a photographic subject image displayed on thedisplay section and then presses a shutter button 1306, the imagingsignal of the CCD at that point in time is transmitted to and stored ina memory 1308. Further, in the digital still camera 1300, a video signaloutput terminal 1312 and an input-output terminal for data communication1314 are provided on the side surface of the case 1302. Then, as shownin the drawing, as necessary, a television monitor 1430 is connected tothe video signal output terminal 1312 and a personal computer 1440 isconnected to the input-output terminal for data communication 1314. Inaddition, a configuration is made in which the imaging signal stored inthe memory 1308 is output to the television monitor 1430 or the personalcomputer 1440 by a predetermined operation. The physical quantity sensor1 which measures a physical quantity such as acceleration or angularvelocity for measuring dropping or inclination of the digital stillcamera 1300 is mounted on the digital still camera 1300. In this manner,the physical quantity sensor 1 described above is mounted, whereby it ispossible to obtain the digital still camera 1300 having highreliability.

In addition, the electronic equipment according to the invention can beapplied to, in addition to the personal computer (the mobile typepersonal computer) of FIG. 19, the mobile phone 1200 of FIG. 20, and thedigital still camera 1300 of FIG. 21, for example, an ink jet typedischarge apparatus (for example, an ink jet printer), a laptop typepersonal computer, a television, a video camera, a video tape recorder,a car navigation device, a pager, an electronic notebook (also includingan electronic notebook with a communication function), an electronicdictionary, a desktop electronic calculator, electronic game equipment,a word processor, a workstation, a video phone, a security televisionmonitor, electronic binoculars, a POS terminal, medical equipment (forexample, an electronic thermometer, a sphygmomanometer, a blood glucosemeter, an electrocardiogram measuring device, an ultrasonic diagnosticdevice, or an electronic endoscope), a fish finder, various measuringinstruments, meters and gauges (for example, meters and gauges of avehicle, an aircraft, or a ship), a flight simulator, or the like.

4. Moving Body

Next, a moving body according to the invention will be described.

FIG. 22 is a perspective view showing an automobile with the moving bodyaccording to the invention applied thereto.

The physical quantity sensor 1 is built in an automobile 1500 and it ispossible to detect the attitude of a car body 1501 by, for example, thephysical quantity sensor 1. A detection signal of the physical quantitysensor 1 is supplied to a car body attitude control device 1502, and thecar body attitude control device 1502 detects the attitude of the carbody 1501 based on the signal and can control the hardness and softnessof a suspension or control a brake of an individual wheel 1503 accordingto a detection result.

The physical quantity sensor, the physical quantity sensor device, theelectronic equipment, and the moving body according to the inventionhave been described above based on the embodiments shown in thedrawings. However, the invention is not limited thereto and theconfiguration of each section can be replaced with any configurationhaving the same function. Further, any other configuration may be addedto the invention.

The entire disclosure of Japanese Patent Application Nos. 2014-165431,filed Aug. 15, 2014, 2014-166926, filed Aug. 19, 2014, 2014-166927,filed Aug. 19, 2014 and 2015-114928, filed Jun. 5, 2015 are expresslyincorporated by reference herein.

What is claimed is:
 1. A physical quantity sensor comprising: asubstrate; a support section which is fixed to the substrate; a movablesection which is connected to the support section through a connectionportion and can oscillate with respect to the support section; and afixed electrode which is disposed on the substrate to face the movablesection, wherein the movable section includes a first mass portion whichis provided on one side with respect to the connection portion, a secondmass portion which is provided on the other side and has larger massthan the first mass portion, a first movable electrode disposed in thefirst mass portion, and a second movable electrode disposed in thesecond mass portion, the fixed electrode includes a first fixedelectrode which is disposed to face the first mass portion, a secondfixed electrode which is disposed to face the second mass portion, and adummy electrode which is disposed to face the movable section so as notto come into contact with the first fixed electrode and the second fixedelectrode and has the same potential as potential of the movablesection, the dummy electrode includes a first dummy electrode providedbetween the first fixed electrode and the second fixed electrode, asecond dummy electrode provided on the side opposite to the first dummyelectrode, of the first fixed electrode, and a third dummy electrodeprovided on the side opposite to the first dummy electrode, of thesecond fixed electrode, and the fixed electrode and the dummy electrodeare disposed such that a capacity offset is smaller than a capacityoffset in a case where distances between the first fixed electrode andthe first and second dummy electrodes and distances between the secondfixed electrode and the first and third dummy electrodes are the same.2. The physical quantity sensor according to claim 1, wherein when adistance between the first fixed electrode and the first dummy electrodeis set to be wl, a distance between the second fixed electrode and thefirst dummy electrode is set to be w2, a distance between the firstfixed electrode and the second dummy electrode is set to be w3, and adistance between the second fixed electrode and the third dummyelectrode is set to be w4, a relationship of wl<w2 and w3=w4 issatisfied.
 3. The physical quantity sensor according to claim 1, whereinwhen a distance between the first fixed electrode and the first dummyelectrode is set to be wl, a distance between the second fixed electrodeand the first dummy electrode is set to be w2, a distance between thefirst fixed electrode and the second dummy electrode is set to be w3,and a distance between the second fixed electrode and the third dummyelectrode is set to be w4, a relationship of w1<w2 and w3<w4 issatisfied.
 4. The physical quantity sensor according to claim 1, whereinwhen a distance between the first fixed electrode and the first dummyelectrode is set to be w1, a distance between the second fixed electrodeand the first dummy electrode is set to be w2, a distance between thefirst fixed electrode and the second dummy electrode is set to be w3,and a distance between the second fixed electrode and the third dummyelectrode is set to be w4, a relationship of w1<w2 and w3>w4 issatisfied.
 5. The physical quantity sensor according to claim 1, whereinwhen a distance between the first fixed electrode and the first dummyelectrode is set to be w1, a distance between the second fixed electrodeand the first dummy electrode is set to be w2, a distance between thefirst fixed electrode and the second dummy electrode is set to be w3,and a distance between the second fixed electrode and the third dummyelectrode is set to be w4, a relationship of w1>w2 and w3<w4 issatisfied.
 6. The physical quantity sensor according to claim 1, whereinthe substrate is a glass substrate.